Unify the server and plugin versions of the generators

pkg/analysis_server/test/src/plugin/protocol_test_utilities.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:analysis_server/plugin/protocol/protocol.dart' as server;
+import 'package:analysis_server/protocol/protocol_generated.dart' as server;
 import 'package:analyzer_plugin/protocol/protocol.dart' as plugin;
 import 'package:analyzer_plugin/protocol/protocol_constants.dart' as plugin;
 import 'package:analyzer_plugin/protocol/protocol_generated.dart' as plugin;
 
 class ProtocolTestUtilities {
   static const List<String> strings = const <String>[
     'aa',
     'ab',
     'ac',
     'ad',
@@ skipping 279 matching lines @@
                   new server.Position(fileName(stringIndex), intIndex++)
                 ],
                 intIndex++,
                 <server.LinkedEditSuggestion>[
                   new server.LinkedEditSuggestion(strings[stringIndex++],
                       server.LinkedEditSuggestionKind.METHOD)
                 ])
           ],
           selection: new server.Position(fileName(stringIndex), intIndex++));
 }